Add installation doc and example of install v1.x binary

README.md

@@ -4,15 +4,40 @@ xtag command finds latest release tag which matched with given tag with `x` wild
 
 ### Installation
 
+```shell
+# Install latest version
+curl -sfL https://raw.githubusercontent.com/haya14busa/xtag/master/install.sh| sh -s
+
+# binary will be in $(go env GOPATH)/bin/
+curl -sfL https://raw.githubusercontent.com/haya14busa/xtag/master/install.sh| sh -s -- -b $(go env GOPATH)/bin [vX.Y.Z]
+
+# or install it into ./bin/
+curl -sfL https://raw.githubusercontent.com/haya14busa/xtag/master/install.sh| sh -s [vX.Y.Z]
+
+# In alpine linux (as it does not come with curl by default)
+wget -O - -q https://raw.githubusercontent.com/haya14busa/xtag/master/install.sh| sh -s [vX.Y.Z]
+```
+
+or you can use go get.
+
 ```shell
 $ go get github.com/haya14busa/xtag/cmd/xtag
 ```
 
-### Usage
+## Usage
 
 ```shell
 $ xtag reviewdog/reviewdog 0.9.x
 0.9.11
 # Use GitHub API token to avoid API rate limit.
 $ export GITHUB_API_TOKEN="xxx"
 ```
+
+### Install v1.x golangci-lint CLI
+
+```shell
+$ curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh -s -- -b $(go env GOPATH)/bin $(xtag golangci/golangci-lint v1.x)
+golangci/golangci-lint info checking GitHub for tag 'v1.15.0'
+golangci/golangci-lint info found version: 1.15.0 for v1.15.0/linux/amd64
+golangci/golangci-lint info installed /home/haya14busa/bin/golangci-lint
+```